1. Field of the Invention
This invention relates, generally, to the field of workpiece moving devices and, more particularly, to a system for moving workpieces which may have variations in dimension.
2. Prior Art
This invention relates generally to the field of precise positioning systems and, more particularly to a system for moving a workpiece from a storage location to a work station on a machine tool and vice versa.
A variety of machine tools have been designed in which the workpiece to be machined is mounted at a work station which is movable relative to the tool which is to perform the operation, e.g. machining or drilling. One such machine tool is a drilling machine which has been designed to drill holes in printed circuit boards. Typically, printed circuit boards have a large number of holes which must be drilled at precise locations in order to enable the proper mounting of electrical components on the circuit boards and/or to permit electrical connections between layers. Computer controlled drilling machines have been developed to permit mass production of circuit boards at high rates. Typically, these drilling machines have a work table (or work station) mounted on a base and movable along both axes of a horizontal plane. The printed circuit boards, or workpieces, are mounted in stacks on the worktable. Movement of the worktable in the horizontal plane positions the circuit boards beneath one or more drill spindles at the precise location where holes are desired. Drilling operations are achieved through vertical travel of the drill spindle.
In addition, to expedite and/or automate the operation, it is desirable to provide means for moving the stacks of boards from a storage area to the worktable. The storage area can be a shelf on a cart, a conveyor belt, or the like. The storage is, typically, placed in near juxtaposition to the work table prior to (and after) the operation is performed. Thus, the stacks of printed circuit boards can be readily moved between the storage areas and the work stations.
In order to expedite and/or automate the overall operation, it is desirable to provide a means for easily and accurately moving the stacks of circuit boards from a storage area to the work table and vice versa.